Power boring bits are widely employed for rapid drilling of medium to large size holes in wood, plastic and the like. Over the years, various techniques have been proposed for assembling a separately formed disc to an elongated shank or bit providing the pointed tip portion. Illustrative of various structures are those shown in Wilson U.S. Pat. Nos. 2,576,376 granted Nov. 27, 1951, 2,577,987 granted Dec. 11, 1951 and 2,593,823 granted Apr. 22, 1952; De Liso Pat. No. 2,962,066 granted Nov. 29, 1960; and Mackey Pat. No. 3,165,131 granted Jan. 12, 1965.
It has been recognized that significant economic advantages could be obtained by the use of cutting discs which might be formed from sheet metal stock by suitable punching, machining and grinding operations. Among the problems that have been encountered in fabricating and assembling such composite power boring bits have been obtaining a satisfactory bond between the two components to prevent relative displacement, locating the cutting edge of the disc relative to the cutting edge of the point, providing adequate means for removal of the turnings, and achieving satisfactory transition of the cutting edge action from the point to the disc.
It is an object of the present invention to provide a novel power boring bit which is fabricated relatively economically and relatively easily from rod or bar stock for the shaft member and from sheet stock for the disc member.
It is also an object to provide such a power boring bit wherein the disc member is securely engaged to the shaft member in a manner substantially ensuring against relative displacement.
Another object is to provide such a power boring bit in which there is achieved smooth transition between the cutting action provided by the point and the cutting action provided by the disc.